It is known in the art relating to welding that the welding wire (consumable electrode) used for welding applications, such as automated manufacturing processes, may be stored in bulk drum packages. Bulk drum packages of welding wire allow for prolonged, continuous dispensing of welding wire, and the package protects the welding wire from airborne contaminants that are present in the manufacturing environment.
During welding, such as with a GMAW (gas metal arc welding), MIG (metal inert gas) or similar welding torch, welding wire dispensed from the bulk drum package is loaded into a wire feeder which feeds the welding wire to the welding torch. If a dispensing failure occurs, such as if the welding wire becomes tangled inside the drum, the welding process must be halted until the failure is corrected by a human operator.
A typical cause of wire tangling in the bulk drum package, especially in the case of aluminum welding wire, is simultaneously de-coiling of more than one coil loop (i.e., lap) of wire. The loose laps expend by the inherent residual torque, and some laps may overlap each other and become tangled. When the wire laps are pulled from the central aperture, more than one lap may be pulled out simultaneously, and eventually tangle at the outlet port of the drum package.
A conventional solution to this tangling problem is to place a lid on top of the coiled welding wire in the package, so that the weight of the lid holds the coils and restricts the coils from prematurely lifting up during dispensing. The lid, however, is limited in its weight as the weight of the lid increases the pulling force required to dispense the wire. A heavy lid may cause the wire, especially aluminum wire, to bend when it is pulled out of the package. On the other hand, a lightweight lid may be lifted and tilted at its outer wedge when wire near the outer diameter of the package is pulled out. The lifting of the lid releases the holding force on the coiled wire underneath the lid and thus increases the chance of laps becoming loose and tangled.
More specifically, the welding wire is typically packed eccentrically so that adjacent layers (i.e., adjacent laps) have different circumferential positions such that the centers of the adjacent layers are offset from each other. Multiple layers of individual laps are built up in the package to form a column of welding wire having an outside diameter and an inside diameter defined by the eccentric, stacked layers of laps. Each individual lap of wire has point along its circumference that is close to the column outside diameter and a point that is close to the column inside diameter. During dispensing using a conventional lid, the wire forming the lap behaves differently along the lap. The basic structure of a conventional lid is a ring that covers the wire column. The wire is dispensed from an inside aperture of the lid, and pulled upwards to the drum outlet. The wire is held under the lid at the point that is close to the column outside diameter, while the wire is loosely held or not held at all at the point that is closed to the column inside diameter. Consequently, the pulling force on the wire is high when the wire is pulled at the outside diameter point and low when the wire is pulled at the inside diameter point. Thus, as the wire is dispensed and pulled from the outside diameter point of a lap, the upwards pulling force on the wire and the friction between the wire and the lid cause the lid to tilt and separate from the wire column. The loss of holding force due to the separation of the lid from the wire column can release an adjacent lap that has its circumference at the inside diameter of the wire column at the opposite, non-lifted side of the lid, because there is little to no holding force applied to this adjacent lap.
The pulling angle on the welding wire from the wire column to the outlet of the package is affected by the distance from the wire column to the package outlet. As this distance increases during dispensing (due to consumption of the wire from the top of the column down), the pulling forces increase to due an increase in the angle between the welding wire and the package outlet. Therefore, a low wire level in the package corresponds to a sharp pulling angle and thus an increased chance in the lid being lifted from the column. The change of lid lift also increases as the welding wire speed increases.
Because the container and packaged welding wire do not rotate during wire dispensing, the wire has a residual torque that needs to be released by twisting when it is dispensed. The clamping of the feeding rollers of the wire feeder and the friction inside the welding torch prevent the wire from twisting freely. The welding wire cannot twist until a certain amount of torque is built up. This built-up torque as well as the frictional force of an adjacent lap that is being pulled upwards for dispensing, causes a free lap (not being held by a lid as described above) to become loose within the package. The loose lap becomes smaller in diameter as the adjacent lap is pulled out of the package outlet. When the diameter of the loose lap decreases beyond a certain value and travels close enough to the package outlet, the loose lap of wire cannot normalize itself and becomes tangled, thereby causing the wire to jam at the package outlet. As stated above, this effect is more significant for aluminum wire because the wire is soft and the coefficient of friction of the wire is high.
There are also known methods of dispensing wire from a reel, where the wire is packed/coiled to the outside of a spool or reel. However, aluminum welding wire cannot be packed in an open reel due to its sensitivity to the environment.